Test launcher: add histograms

base/test/launcher/test_launcher.cc

Index: base/test/launcher/test_launcher.cc
diff --git a/base/test/launcher/test_launcher.cc b/base/test/launcher/test_launcher.cc
index 1e2a95b0daa7a6813d8a844d7a46885a2ded8a03..9195606b57dbd70ce9b21cdba8be8ac16d1cbcb6 100644
--- a/base/test/launcher/test_launcher.cc
+++ b/base/test/launcher/test_launcher.cc
@@ -21,6 +21,8 @@
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/message_loop/message_loop.h"
+#include "base/metrics/histogram_macros_local.h"
+#include "base/metrics/statistics_recorder.h"
 #include "base/process/kill.h"
 #include "base/process/launch.h"
 #include "base/run_loop.h"
@@ -75,6 +77,9 @@ namespace {
 // for any reason, e.g. early exit because of too many broken tests.
 const char kUnreliableResultsTag[] = "UNRELIABLE_RESULTS";
 
+// Name of the local histogram to measure test output size.
+const char kOutputSizeHistogramName[] = "TestLauncher.TestOutputSize";
+
 // Maximum time of no output after which we print list of processes still
 // running. This deliberately doesn't use TestTimeouts (which is otherwise
 // a recommended solution), because they can be increased. This would defeat
@@ -542,6 +547,11 @@ bool TestLauncher::Run() {
 
   MaybeSaveSummaryAsJSON(std::vector<std::string>());
 
+  std::string output_histogram;
+  StatisticsRecorder::WriteGraph(kOutputSizeHistogramName, &output_histogram);
+  fprintf(stdout, "%s", output_histogram.c_str());
+  fflush(stdout);
+
   return run_result_;
 }
 
@@ -577,6 +587,9 @@ void TestLauncher::OnTestFinished(const TestResult& original_result) {
 
   TestResult result(original_result);
 
+  LOCAL_HISTOGRAM_CUSTOM_COUNTS(
+      kOutputSizeHistogramName, result.output_snippet.length(),
+      1, 10000000, 50);
   if (result.output_snippet.length() > kOutputSnippetBytesLimit) {
     if (result.status == TestResult::TEST_SUCCESS)
       result.status = TestResult::TEST_EXCESSIVE_OUTPUT;
@@ -946,6 +959,8 @@ bool TestLauncher::Init() {
   results_tracker_.AddGlobalTag("CPU_64_BITS");
 #endif
 
+  StatisticsRecorder::Initialize();
+
   return true;
 }